This invention relates to an adjustable tension fastener and more particularly to an adjustable elastic tie-down cord typically referred to as a bungee or shock cord.
Tension fasteners are used, for example, for securing covers and various other items to boats, cars, trucks, motorcycles, and the like, for bundling packages, and for tying loose items together. The most common prior art devices include linear elastic cords having hooks bound at each end.
Tie-down stretch or tension cords of the prior art have a number of disadvantages. First, they lack adjustability relative to the tension necessary to accomplish the task. The hooks are permanently attached to each end of a fixed length of elastic rope and the elastic rope in many situations must be stretched excessively thereby applying more pressure to the load than desired and thereby exceeding the stretch limits of the cord.
A number of adjustable tie-down stretch or tension cords have been developed but are complex and expensive in construction and in some instances leave a dangling loose end in the cord which may become entangled, for example in the spokes of a vehicle wheel, or tripped upon.
In addition, the hook design for the tension cords of the prior art do not provide adequate abrasion resistance, are overly subject to breakage, particularly in cold weather, to rust and corrosion and are not sufficiently abrasive resistant.
Also, hook designs for the tension cords of the prior art are shaped such that they are not capable of being hooked into small holes or passages in hard flat surfaces.
It is a principal object of the present invention to provide an adjustable elastic tie-down cord which is devoid of these aforementioned disadvantages.
The adjustable elastic tie-down cord of the present invention includes an elongated stretchable elastic cord having two end portions with a hook secured to one of the end portions. A line adjusting retainer bar is provided with two spaced passages which pass through the bar and slidably receive different portions of the cord whereby an adjustable loop in the cord is formed on one side of the bar for selectively adjusting the overall length of the cord.
The other end of the cord is provided with a stop, such as a stop knot, for preventing the cord end portion from passing through its respective passage in the line adjusting retainer bar. A hook is slidably received on the cord in the loop section.
Adjustment of the overall length of the cord is accomplished by merely sliding the cord end which is terminated with the hook, in or out of its respective passage through the line adjusting retainer bar to correspondingly adjust the size of the loop. This adjustment is made when the cord is not under tension.
Once the adjustment has been accomplished, and tension is applied to the cord through the respective hooks, the line adjusting retainer bar is forced to turn sideways such that it is substantially in line with or alignment with the cord. The resistance thus applied by the retainer bar to the tensioned elastic cord prevents the cord from further slipping through its passage in the retainer bar and prevents the prealigned adjustment from slipping.
To further assist in preventing the cord from slipping through its passage in the retainer bar, the passage through which the elastic cord normally slides for adjustment is provided with annularly eased edge openings for engagement with the elastic cord, and in addition, sharp protrusions are further provided at points of engagement for penetrating the elastic cord and thereby assisting in locking the elastic cord in position. These eased passage entrances where the protrusions are provided are also preferably provided as concave annular recesses which permits the protrusions to more effectively penetrate the elastic cord and also provides sharp edges to better engage the cord and prevent it from slipping.
The hooks are preferably constructed of stainless steel in order to prevent rusting and corrosion and they are further preferably provided with a thick rubber coating for assisting in the prevention of abrasion and for protection of the metal hooks.
In addition, the hooks are also preferably C-shaped with parallel shank and terminating end portions whereby the hook can be easily hooked into a small hole in a hard flat surface.
In addition, the passages through the line adjusting retainer bar are preferably provided with eased edged openings for thereby assisting in gripping of the cord by the bar while also assisting in prevention of abrasion to the cord.
The line adjusting retainer bar is also preferably wedged shaped whereby thickness of the bar, and of the passage therethrough which receives the stopped end portion of the cord, is thinner than that for the other passage.
This wedge shaped configuration permits the retainer bar to lay flatter and to more sharply engage the cord at an acute angle to assure prevention of slippage of the cord when the cord is applied under tension.